This invention relates generally to methods of repairing electrical wiring harnesses and, more specifically, to methods of repairing the overbraid for metal overbraided wiring harnesses.
Wiring harnesses are used in the operation of most engines to electrically couple the engine and associated equipment to one another. In aircraft jet engines, the wiring of the harnesses is often protected by an outer metal overbraid. Although satisfactory as installed, the high temperature, high vibration and associated chafing conditions experienced by the electrical harnesses during engine operation tend to cause the metal overbraid to become worn or frayed. Currently, it is difficult to repair a damaged wiring harness in the field, particularly without removing the harness from the engine for, what is commonly known as, “on wing” repairs. When damaged the harness is usually removed for repair and then replaced. This procedure is expensive and results in downtime for the aircraft.
Methods for splice repair of electrical wiring harnesses are known in the art. U.S. Pat. No. 6,143,986 describes an electrical wiring harness having at least one repair splice means at pre-defined locations in the harness and at predetermined distances from the backshell. The repair splice means allows for easy repair without removing the harness from the engine. However, although repairs may be made on wing, the specific harness of the '986 patent is required. Moreover, it only allows for repairs around the backshell terminations and not mid-span of the harness wiring.
U.S. Pat. No. 5,854,444 discloses a splice kit for repairing shielded cable. The kit comprises crimp ferules and a shielding sleeve to use for splicing together damaged cable. The crimp ferules are applied on either side of the splice site to prevent further unraveling of the wire shielded braid. The central conductor is then spliced together using crimp-type conductor splices. Finally, the repaired portion of the central conductor is protected by placing a preformed shield seal sleeve around the spliced shielded wire. However, repairs by this method are limited by the availability of the kit. Moreover, often times only the overbraid is damaged and in need of repair without requiring splicing of the central conductor.
As can be seen, there is a need for a simple method to repair the overbraid of metal overbraided wiring harnesses that can be accomplished easily with materials that are readily available. It would be advantageous to have a method which allows for ‘on-wing’ repair of the harness eliminating having to remove it from the engine.